Fuel comsumption and exhaust emissions are major problems that concern operation of automotive vehicles of the type having carburetion systems to provide fuel mixture for engine operation. It has been determined that fuel is needlessly consumed during deceleration phases of automotive engine operation and, of the fuel that is needlessly used, a major portion of it is exhausted from the engine in an unburned or poorly combusted condition where it contributes greatly to pollution of the atmospheric environment. Unburned hydrocarbons in the emissions of an internal combustion engine is a key ingredient in the formation of photochemical smog, because hydrocarbons occur a direct result of incomplete combustion, such as occurs at its highest level during high speed deceleration of the engine of an automotive vehicle. In general, hydrocarbon emissions are high when air consumption is low and are relatively low when air consumption of engines is high.
Carbon monoxide present in the emissions of an operating internal combustion engine has been determined to exist at a relatively high level when the automotive engine is operating at idle speed and reaches its highest level during deceleration of the engine. Carbon monoxide is present at its lowest level during acceleration of the engine and at steady speeds, with small peaks occurring as a result of sudden changes in the throttle opening of the carburetor of the engine.
Another ingredient that contributes materially to air pollution is oxides of nitrogen, which exist in the emissions of internal combustion engines as nitric oxide and nitrogen dioxide. The oxides of nitrogen are toxic and also contribute to the formation of photochemical smog. The emission of oxides of nitrogen from operating internal combustion engines rises sharply during acceleration, but has little relation to vehicle and engine speed. The lowest output of oxides of nitrogen has been determined to exist at idle and during deceleration of the engine. A rich mixture, strangely enough, helps reduce the oxides of nitrogen content in exhaust gases.
It is well known that fuel consumption and exhaust emissions are determined in large measure by the operating characteristics of the internal combustion engines of automotive vehicles. When an engine is rapidly accelerated, the compression in the various cylinders of the engine increases substantially, but the presence of vacuum for drawing air and fuel mixture into the intake manifold of the carburetor reduces sharply. As cylinder power pressure increases, the existence of oxides of nitrogen in the exhaust of the automobile is at its highest level while the presence of unburned hydrocarbons and carbon monoxide is at its lowest level. During operation of automotive engines at idle, the compression pressure is quite low, while manifold vacuum increases substantially, thereby causing the cylinder power pressure of the engine to be sufficiently low that improper combustion of the fuel air mixture occurs. Under conditions of idling, the presence of hydrocarbons in the exhaust of the automobile is at its highest level and the presence of carbon monoxide also reaches its peak. It is desirable therefore, to provide an acceleration and deceleration governor system for automotive engines that effectively prevents development of engine operating conditions that cause excessive emissions and excessive fuel consumption during periods of acceleration and deceleration.
Many carburetors are provided with a device, typically referred to as a power valve, that has the effect of injecting an additional quantity of fuel through the main fuel supply system of the carburetor responsive to sensing of an abnormally low vacuum condition (high pressure condition), such as occurs when the throttle linkage of the carburetor is manipulated suddenly to cause rapid acceleration of the vehicle powered by the engine. For example, an intake manifold pressure below 7.5 inches of mercury will typically cause the power valve of the carburetor to actuate, which adds to the fuel mixture of the main fuel circuit of the carburetor the additional fuel supplied by a power valve circuit controlled by the pressure sensitive power valve. Consequently, when an automotive engine is operated at intake manifold pressures between 0 and 7.5 inches of mercury, fuel consumption will be high. The presence of hydrocarbons in the emissions of the engine will also be high during this particular period of engine operation.
During operation of the engine it is necessary to allow the engine to operate at idle speed, but is is well known that combustion is poor and the presence of hydrocarbons and carbon monoxide is at the highest level during idle operation and especially during periods when the engine is decelerating and the fuel mixture supplied to the intake manifold of the engine is at its highest level. It is of course desirable to operate the engine at idle speed as little as possible and to completely eliminate injection of fuel mixture into the engine during periods of engine deceleration.
Accordingly, it is the primary object of the present invention to provide a novel acceleration and deceleration governor system for automotive vehicle engines that terminates the flow of rich idle mixture into the intake manifold of the engine during periods of deceleration.
It is also an important object of the present invention to provide a novel acceleration and deceleration governor system for automotive engines that is responsive to manifold pressure to limit the rate of acceleration of the engine and thereby prevent excessive fuel consumption that otherwise takes place during such acceleration.
Another object of the present invention contemplates the provision of a novel acceleration and deceleration governor system for automotive engines wherein exhaust gas is metered from the exhaust manifold of the engine into the intake manifold to provide for smooth engine operation during transition between acceleration and deceleration phases of engine operation.
It is an even further object of the present invention to provide a novel acceleration and deceleration governor system for automotive engines that is controlled responsive to manifold vacuum and responsive to the position of the throttle linkage of the carburetor associated with the automotive engine.
Among the several objects of the present invention is noted the provision of a novel acceleration and deceleration governor system for automotive engines wherein the fuel mixture allowed to enter the intake manifold of the engine is effectively limited during periods of engine acceleration regardless of the position of the throttle valve of the carburetor associated with the engine, in order that fuel consumption and exhaust emissions will be auotmatically maintained within an acceptable range during acceleration.
It is also an important object of the present invention to provide a novel acceleration and deceleration governor system for automotive engines that functions responsive to intake manifold pressure conditions and includes vacuum cut-off means that renders the manifold pressure ineffective during certain desirable phases of engine operation.
Other and further objects, advantages and features of the present invention will become apparent to one skilled in the art upon consideration of the written specification, the attached claims and the annexed drawings. The form of the invention, which will not be described in detail, illustrates the general principals of the invention, but it is to be understood that this detailed description is not to be taken as limiting to the scope of the present invention.